Transfer device and image forming apparatus including the same

Abstract

A transfer device including an intermediate transfer belt provided to extend in an arranged direction of a plurality of photosensitive drums, and primary transfer rollers each transferring a toner image formed on a corresponding one of the plurality of photosensitive drums to the intermediate transfer belt, each of the primary transfer rollers being moved between a position causing the intermediate transfer belt to be in contact with the photosensitive drums and a position causing the intermediate transfer belt to be separated from the photosensitive drums, each of the primary transfer rollers being rotatably supported by a movable member which includes an abutting portion which regulates a position of the primary transfer roller, the abutting portion abutting on an abutted member whose positional relationship with the photosensitive drum is defined such that the position of the abutted member causes the intermediate transfer belt to be in contact with the photosensitive drum.

1. A transfer device, comprising:
 an intermediate transfer belt provided to extend in an arranged direction of a plurality of photosensitive drums; 
 primary transfer rollers each configured to transfer a toner image formed on a corresponding one of the plurality of photosensitive drums to the intermediate transfer belt and being rotatably supported by a movable member including an abutting portion which regulates a position of the primary transfer roller, wherein each of the primary transfer rollers is configured to be moved between a first position causing the intermediate transfer belt to be in contact with the photosensitive drums and a second position causing the intermediate transfer belt to be separated from the photosensitive drums; 
 a plate connected to the movable member via a spring, wherein the plate is configured to move in a direction substantially parallel to a suspension direction of the intermediate transfer belt to move the spring to rotate the movable member around a first axis; and 
 an abutted member positioned above the movable member and including an abutted surface on which the abutting portion is abutted in the first position and which is configured to regulate a positional deviation of the primary transfer rollers in a direction perpendicular to the suspension direction of the intermediate transfer belt, wherein 
 a center distance between a center axis of each one of the photosensitive drums and a center axis of a corresponding one of the primary transfer rollers at the first position is set to be larger than a sum of radiuses of the each one of the photosensitive drums and the corresponding one of the primary transfer rollers. 
 
   
   
     2. The transfer device according to  claim 1 , wherein the abutted surface is a flat surface parallel with the suspension direction of the intermediate transfer belt. 
   
   
     3. The transfer device according to  claim 2 , wherein the abutted member is formed by a portion of a case which houses the photosensitive drums. 
   
   
     4. The transfer device according to  claim 2 , wherein the abutted member is formed by a portion of a shaft bearing member for the photosensitive drums. 
   
   
     5. The transfer device according to  claim 2 , wherein,
 the first position and the second position exist in a direction perpendicular to the suspension direction of the intermediate transfer belt, and 
 the movable member is configured to cause the primary transfer roller to reciprocate between the first position and the second position. 
 
   
   
     6. The transfer device according to  claim 5 , wherein the abutting portion has a circular arc shape. 
   
   
     7. The transfer device according to  claim 6 , wherein,
 the movable member comprises an arm which is rotated about a rotation shaft, and 
 the primary transfer roller is located between the abutting portion and the rotation shaft. 
 
   
   
     8. The transfer device according to  claim 2 , wherein the movable member is configured to cause the primary transfer roller to reciprocate in an arc between the first position and the second position. 
   
   
     9. The transfer device according to  claim 8 , wherein the abutting portion has a circular arc shape. 
   
   
     10. The transfer device according to  claim 9 , wherein,
 the intermediate transfer belt is located below the photosensitive drums, and 
 the abutting portion is positioned to protrude upwardly from the intermediate transfer belt at the first position. 
 
   
   
     11. The transfer device according to  claim 8 , wherein,
 the movable member comprises an arm which is rotated about a rotation shaft, and 
 the primary transfer roller is located between the abutting portion and the rotation shaft. 
 
   
   
     12. An image forming apparatus comprising the transfer device as recited in  claim 1 . 
   
   
     13. A transfer device, comprising:
 a photosensitive unit including a casing and at least one photosensitive drum positioned in the casing; 
 an intermediate transfer belt configured to receive a transfer image from the at least one photosensitive drum; 
 at least one primary transfer roller configured to transfer the toner image from the at least one photosensitive drum to the intermediate transfer belt; 
 a movable member configured to rotatably support the at least one primary transfer roller, and including an abutting portion which regulates a position of the at least one primary transfer roller by abutting against the photosensitive unit to cause the intermediate transfer belt to be in contact with the at least one photosensitive drum; and 
 a plate connected to the movable member via a spring, wherein the plate is configured to move in a direction substantially parallel to a suspension direction of the intermediate transfer belt to move the spring to rotate the movable member around a first axis. 
 
   
   
     14. The transfer device according to  claim 13 , wherein, when the abutting portion is separated from the photosensitive unit, the intermediate transfer belt is separated from the at least one photosensitive drum. 
   
   
     15. The transfer device according to  claim 13 , wherein the abutting portion abuts against the casing to cause the intermediate transfer belt to be in contact with the at least one photosensitive drum. 
   
   
     16. The transfer device according to  claim 13 , wherein,
 the intermediate transfer belt is located below the at least one photosensitive drum, and 
 the abutting portion is positioned to protrude upwardly from the intermediate transfer belt to abut against the photosensitive unit. 
 
   
   
     17. A transfer device, comprising:
 a photosensitive unit including a casing and at least one photosensitive drum positioned in the casing; 
 an intermediate transfer belt configured to receive a transfer image from the at least one photosensitive drum; 
 at least one primary transfer roller configured to transfer the toner image from the at least one photosensitive drum to the intermediate transfer belt; and 
 a movable member configured to rotatably support the at least one primary transfer roller, and including an abutting portion which regulates a position of the at least one primary transfer roller by abutting against the photosensitive unit to cause the intermediate transfer belt to be in contact with the at least one photosensitive drum, wherein 
 the photosensitive unit includes a shaft on which the at least one photosensitive drum is positioned and a shaft support unit configured to support the shaft, and 
 the abutting portion abuts against the shaft support unit to cause the intermediate transfer belt to be in contact with the at least one photosensitive drum. 
 
   
   
     18. The transfer device according to  claim 17 ,
 wherein the abutting portion of the movable member is configured to be positioned on a same side of the intermediate transfer belt as the at least one photosensitive drum when the intermediate transfer belt is in contact with the photosensitive drum. 
 
   
   
     19. The transfer device according to  claim 17 ,
 wherein the abutting portion and the shaft support unit each include a contacting portion, and one of the contacting portions has a flat surface and another one of the contacting portions has a circular arc shape. 
 
   
   
     20. An image forming apparatus, comprising:
 a photosensitive unit including a casing and at least one photosensitive drum positioned in the casing; 
 an intermediate transfer belt configured to receive a transfer image from the at least one photosensitive drum; 
 at least one primary transfer roller configured to transfer the toner image from the at least one photosensitive drum to the intermediate transfer belt; and 
 a movable member configured to rotatably support the at least one primary transfer roller, and including an abutting portion which regulates a position of the at least one primary transfer roller by abutting against the photosensitive unit to cause the intermediate transfer belt to be in contact with the at least one photosensitive drum, wherein 
 the photosensitive unit includes a shaft on which the at least one photosensitive drum is positioned and a shaft support unit configured to support the shaft, and 
 the abutting portion abuts the shaft support unit to cause the intermediate transfer belt to be in contact with the at least one photosensitive drum. 
 
   
   
     21. The image forming apparatus according to  claim 20 ,
 wherein the abutting portion of the movable member is configured to to be positioned on a same side of the intermediate transfer belt as the at least one photosensitive drum when the intermediate transfer belt is in contact with the photosensitive drum. 
 
   
   
     22. The image forming apparatus according to  claim 20 ,
 wherein the abutting portion and the shaft support unit each include a contacting portion, and one of the contacting portions has a flat surface and another one of the contacting portions has a circular arc shape. 
 
   
   
     23. An imaging forming apparatus, comprising:
 at least one photosensitive drum; 
 an intermediate transfer belt configured to receive a toner image from the at least one photosensitive drum; 
 at least one primary transfer roller configured to transfer the toner image from the at least one photosensitive drum to the intermediate transfer belt and to be moved between a position causing the intermediate transfer belt to be in contact with the at least one photosensitive drum and a position causing the intermediate transfer belt to be separated from the at least one photosensitive drum; and 
 a movable member configured to rotatably support the at least one primary transfer roller, the movable member including a part disposed at a position on a same side of the intermediate transfer belt as the at least one photosensitive drum when the primary transfer roller is in the position causing the intermediate transfer belt to be in contact with the photosensitive drum. 
 
   
   
     24. The image forming apparatus according to  claim 23 ,
 wherein the part comprises an abutting portion provided on the movable member, the part being contactable with an abutted portion. 
 
   
   
     25. The image forming apparatus according to  claim 24 , further comprising:
 a casing containing the photosensitive drum, 
 wherein the abutting portion is in contact with the casing to regulate the position of the primary transfer roller at the position where the primary transfer roller causes the intermediate transfer belt to be in contact with the photosensitive drum. 
 
   
   
     26. The image forming apparatus according to  claim 25 ,
 wherein the abutting portion and the casing each include a contacting portion, and one of the contacting portions has a flat surface and another one of the contacting portions has a circular arc shape. 
 
   
   
     27. The image forming apparatus according to  claim 24 , further comprising:
 a photosensitive unit including the photosensitive drum, a shaft on which the photosensitive drum is positioned, and a shaft support unit configured to support the shaft, 
 wherein the abutting portion is in contact with the shaft support unit to regulate the position of the primary transfer roller at the position where the primary transfer roller causes the intermediate transfer belt to be in contact with the photosensitive drum. 
 
   
   
     28. The image forming apparatus according to  claim 27 ,
 wherein the abutting portion and the shaft support unit each include a contacting portion, and one of the contacting portions has a flat surface and another one of the contacting portions has a circular arc shape.